Effects of water soluble extract from the dead leaves of deciduous trees on the growth control of toxic cyanobacteria like Microcystis aeruginosa


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Shimada K., Kitamura N., Yoshida Y., Matsushima H., Asada Y.

10th International Conference on Modelling, Monitoring and Management of Water Pollution, Bucharest, Romania, 9 - 11 June 2010, vol.135, pp.71-74 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 135
  • Doi Number: 10.2495/wp100071
  • City: Bucharest
  • Country: Romania
  • Page Numbers: pp.71-74

Abstract

Because of the toxic microcystin from Microcystis aeruginosa (Ma) in eutrophicated lakes and reservoirs, effective counter measures against its excessive growth have been widely called for Recent research on the growth control of Microcystis was conducted especially concerning the effects of straw and emergent plants The authors have discussed that the water soluble extract (WSE) from the dead leaves of deciduous trees like cherry (Purunus Yedoensis) and maple (Acer buergerianum Miq) bring about a clear effect on the growth control of Ma The WSE solutions from the dead leaves of cherry and maple trees were added to an Ma culture solution to set the initial condensed tannin loading intensity (CTLI) per unit cell at about 26 pg-CT/cell, and then, the daily change of the Ma cell concentration was observed Accordingly, the WSE addition resulted in controlling the cell concentration and its influence was clearly affected by the initial CTLI level The condensed tannin (CT) in the WSE solution was preferentially separated to produce a CT fraction (CTF) solution by use of casein/acetone, and thus the CTF solution also caused a good growth control The WSE fractioning treatment resulted in separating the CT substance from the WSE solution As for the growth control tests using the WSE and CTF solutions, the initial CTLI level was set at between 13 to 18 pg-CT/cell, and accordingly the CT effect was confirmed in terms of the growth control similarly in both the WSE and the CTF addition cases Therefore, the results imply that the CT extracted from the dead leaves is the major growth control factor of M a, and thus the dead leaves of deciduous trees function as an effective growth control agent